1. Field of the Invention
The present invention relates to the field of liquid crystal display technology, and in particular to a pixel structure.
2. The Related Arts
Liquid crystal displays have a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and are thus widely used. Most of the liquid crystal displays that are currently available in the market are backlighting liquid crystal displays, which comprise a liquid crystal display panel and a backlight module. The operation principle of the liquid crystal display panel is that, with liquid crystal molecules interposed between two parallel glass substrates, a driving voltage is applied to the two glass substrates to control the rotation direction of the liquid crystal molecules in order to refract out light emitting from the backlight module to generate an image. Since the liquid crystal display panel does not emit light by itself, light must be provided from the backlight module in order to normally display the image. Thus, the backlight module is one of the key components of a liquid crystal display. The backlight modules can be classified in two types, namely a side-edge backlight module and a direct backlight module, according to the position where light gets incident. The direct backlight module comprises a light source, such as a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED), which is arranged at the backside of the liquid crystal display panel to form a planar light source directly supplied to the liquid crystal display panel. The side-edge backlight module comprises an LED light bar, serving as a backlight source, which is arranged at an edge of a backplane to be located rearward of one side of the liquid crystal display panel. The LED light bar emits light that enters a light guide plate (LGP) through a light incident face at one side of the light guide plate and is projected out of a light emergence face of the light guide plate, after being reflected and diffused, to form a planar light source for the liquid crystal display panel.
The present-day liquid crystal display panels, particularly large-sized liquid crystal display panels, often show color shifting at large view angles. The larger the view angle is, the more severe the color shifting will be. In order to expand the view angle and suppress color shifting, a low color shift design that is often adopted for the large-sized liquid crystal display panels is to increase the number of domains making up of a pixel. A pixel is commonly divided into four domains and if a pixel is partitioned to two pixel zones, namely a main pixel zone and a sub pixel zone, then the number of domains is increased to eight. This increases the view angle and improves color shifting at large view angles.
The main pixel zone and the sub pixel zone are powered by means of two or more different thin-film transistors. Reference is now made to FIGS. 1 and 2, which are respectively a schematic view of a pixel structure adopting a low color shift design and an equivalent circuit diagram thereof. A pixel 102 is partitioned into a main pixel zone 104 and a sub pixel zone 106. When the gate line of number Gn is activated, a first thin-film transistor (or main thin-film transistor) 202 and a second thin-film transistor (or sub thin-film transistor) 204 are respectively operated to convey electrical charges to a first storage capacitor Cst1 of the main pixel zone 104 and a second storage capacitor Cst2 of the sub pixel zone 106, which collectively constitute the pixel 102. When the gate line of number Gn is de-activated and the gate line of number Gn+1 is activated, a third thin-film transistor (or charge sharing thin-film transistor) 206 is switched on to allow the electrical charges of the second storage capacitor Cst2 of the sub pixel zone 106 to partly release to a charge sharing capacitor Cb. This causes a differential potential between the main pixel zone 104 and the sub pixel zone 106, achieving the purposes of suppressing color shifting.
A pixel structure having such an arrangement can achieve suppressing of color shifting; however, three thin-film transistors and two gate lines are needed for each pixel to control the charging of the pixel and this causes a great loss of aperture ratio of the pixel.